Chimps are great. It’s official. Political correctness requires me to like chimps. Nevertheless, I reserve the right to dislike them. Various television presenters have told me that chimps are gentle, unlike we nasty violent humans. I have never in my adult life hit anyone, nor been hit by anyone. My experience of human life is peaceful. Chimps in the wild go on raiding adventures, and kill and maim each other quite a lot. Killing the young offspring of one’s rivals is commonplace in the ape world. I’m glad to say that it isn’t in the human world nearly so common.
Many television programmes have sought to convince me that chimps are intelligent in much the same way that humans are. I have been shown clever chimps who can have conversations in human-like languages. More recent scientific revelations have burst this balloon. The few gifted chimpanzees who were selected for very lengthy and intensive training in language never really managed much more than they would in the wild: a handful of simple gestures and whoops.
When the science of genetics got going, chimp apologists started to argue that since we humans share so much DNA in common with chimpanzees, we should therefore all love chimpanzees, and afford them the same rights as humans. This is a bit like saying that we should all love Hitler, because he was just like us.
Yes, we do share much of our DNA with chimpanzees. However, we also share most of the same DNA with fruit flies. Is swatting a fruit fly to become treated as a case of murder?
Cytochrome C amino acid substitutions correlate very well with DNA substitutions. Since the cytochrome C molecule has 104 amino acids, the figures given below are very close to the percentage figures. The numbers are the number of amino acids in Cytochrome C for each species that are identical to those found in humans.
So we are somewhere around 68% genetically the same as a moth. Does that make you feel better or worse? It should do neither. The world hasn’t changed.
Here are two theories I have come up with to counter the argument which says that we should love chimps because they have similar DNA. The amount we share varies from individual to individual. Some of us are bit more chimpy than others, but a typical figure is 98.4%.
The inherited gobbledegook argument
A man is composed of flesh, bone, tooth and sinew. He must have DNA capable of creating these materials. He has a skeleton with a particular configuration, a circulatory system, lungs, liver, two eyes, a brain. A donkey is the same in all these respects. A man is a donkey, only a slightly different shape, and with various refinements to digestion, and instinct. I would expect that the DNA which codes for a donkey to be mostly the same as that which codes for a man. Further, given that donkeys and men share ancestry, I would also expect that a lot of the DNA would be shared, but much also would be irrelevant.
Imagine a creature which lived in the rivers and had scales on its skin. After some while, an amphibious version of this creature evolves, and it spends time on the land. After many generations, the species is no longer amphibious, and never goes in the water. It still has scales, though. A mutant member of this species develops a mutation which means that the scale-producing DNA never gets switched on. It has no scales, and it reproduces. After a while, the whole species loses its scales.
The genes which code for how to make scales are still being passed on from generation to generation. However, the selective pressure to copy them accurately each time has been removed. A creature could now inherited flawed instructions on how to make scales, but this wouldn’t harm it since it never used that part of its DNA anyway. After many generations, more and more mistakes accumulate in the scale-producing DNA, which gradually turns into complete gobbledegook.
This species becomes the ancestor of both donkeys and men. Both donkeys and men inherit the same faulty scale-DNA. Donkeys and men continue to evolve and the scale producing DNA mutates further in both species, but in a different way in each. The difference in the scale-producing DNA in men and donkeys can be measured as part of the difference between donkeys and men. However, since this DNA codes for something of no use to either donkeys or men, this difference is irrelevant. It tells us nothing of how similar humans and donkeys are. It does tell us something of how much shared ancestry we have, but that’s like saying that a violin and a wardrobe are the same because they were both made of wood from the same tree. Try playing a wardrobe and see how good a tune you get.
The genes-as-language argumentRead these two passages:
Did you spot the difference? There are 53 words and 303 characters in each of those two passages. Only one word was different, and only four characters. This means that the two passages are about 98% the same. Are they 98% the same in meaning? I would argue that they are not. “Never” and “often” are rather contradictory. Zlarg would probably be unimpressed to find that his people had excused their contrary behaviour on the grounds that their version of this passage was almost the same as his.
DNA is written in a language, Gattaca. The alphabet has just four letters. A long stream of DNA which codes for some aspect of a creature can be altered by just a tiny bit in terms of As, Gs, Cs and Ts, but the effect can be huge. Saying that a creature must be just like another because they have lots of shared DNA is stupid. Saying that we should love a creature because it shares lots of our genes is dafter still. A gnu has most of the same genes as a lion, but I doubt that this fact will patch up relations between those species. Imagine a species which is exactly like humans except for one small change which made them enormously more aggressive. Would you love this species, just because it has 99.99% similar DNA? You might if you want to die.
It now seems that perhaps just fifty genes are responsible for the differences between human and chimpanzee brains. Research being carried out all round the world into human and chimpanzee genetics now may lead us to learn what it is that makes us human. Since chimpanzees are so very similar to us, one way to discover the function of a human gene, is to put it in a chimp and see what happens. One practical result of such research would be in boosting human immunity to disease. Chimpanzees are much less vulnerable to AIDs, cholera, malaria, cancer, and influenza. There are chemicals on the surface of every cell in a chimps body which differ from those on human cells. This seems likely to have something to do with the vulnerability of humans to these complaints. It is also possible that the same chemicals on human cells affect brain function quite significantly. Nature gives with one hand and takes away with the other. Nevertheless, the potential for new drugs and gene therapy is enormous. So, perhaps chimps aren’t so bad after all.